サテライト液滴の表面張力振動を利用した液体物性測定手法の開発

抄録

A micro-meter-sized droplet called satellite droplet can be generated with capillary bridge breakup method. The droplet spontaneously oscillates in an axisymmetric oblate-prolate shape due to surface tension as the restoring force. The oscillation is damped by viscous effects, and the droplet eventually becomes spherical. The period and decay time of the oscillation can be related surface tension and viscosity of a liquid, respectively. Applying these relations, we have developed a new method to measure liquid properties under contactless environment. In this study, satellite droplet oscillations are detected by a photodetector to obtain the period and decay time. At the same time, a single image of the droplet settled in a spherical shape is captured using a CMOS camera to obtain droplet radius. Based on these data, we determined the surface tension and viscosity of liquids and evaluated the accuracy of the measurement. As a result, we obtained both surface tension and viscosity values close to the literature values using distilled water, octane, tetradecane, and hexadecane as a test liquid.